


On His Behalf

by sansual



Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell (Undertale), Anal Sex, Choking, College AU, Dom/sub, Double Penetration, F/M, Female Reader, Friends to Lovers, Gaster is an ASSHOLE in this okay, Light BDSM, Love Triangles, Multi, Porn With Plot, Professor Kink, Pure Smut, Sexual Tension, Teacher/Student, Threesome - F/M/M, au where the monsters never went underground, but he's hot so, listen i wanted to put a daddy kink in here but it didn't fit but i just want that noted
Language: English
Status: In-Progress
Published: 2020-03-01
Updated: 2020-02-29
Packaged: 2021-02-28 08:42:14
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 10,936
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22967119
Author URL: https://archiveofourown.org/users/sansual/pseuds/sansual
Summary: Going to college is an experience in itself. Going to the same university as your best friend is a completely different adventure.You and your childhood friend, Rus, sign up for a magic-biology class together, taught by a Dr. W.D. Gaster. The professor's a skeleton, just like your best friend, but he's attractive in a whole different way than Rus is. Amidst feelings you didn't know you had, you start to want for your professor.It doesn't help that he seems to have it out for Rus. The lanky skeleton's having a hard time passing, and things aren't adding up.You can't let your best friend fail.What are you going to do to help him?(jk we all know what we're gonna do)
Relationships: Papyrus (Undertale)/Reader, Swapfell Papyrus/Reader, W. D. Gaster/Reader
Comments: 6
Kudos: 104





	1. Teacher's Pet

  


Going to college is an experience in itself. Going to the same university as your best friend is a completely different adventure.

You first met Rus in middle school, back when you were both so angsty and afraid of everything. Neither of you really fit in with the others, so you did what most of the loners did and grouped up together, just the two of you. The lanky skeleton and that one weird girl. 

You made it through high school like that, too. For prom you wore an indigo dress, and the tie he wore matched. It’s not like you stayed at the dance very long, though. The two of you were never the going-out type, much preferring to spend afternoons on the couch with a video game or two.

Other friends came and went, with their own agendas and drama, and it’s not to say that you didn’t enjoy their company. At the end of the day, though, it was always Rus driving you home.

You’d be lying if you said you never thought about dating him. He’s attractive in that slick, punk way that makes you stare from time to time. He’s sweet, too, almost surprisingly so, given his appearance and his rep. It’s not just to you, but to others, and his brother, too. 

The topic of dating has come up with you a few times over the years, always from someone else making a well-intended comment. 

“You two are so cute together,” they always say. “Have you even _thought_ about it?”

And Rus always knows how to respond. “we have, sure. but _____’s my best friend, and we don’t wanna risk losing that just to try something that may or may not work.” 

And he’s right, every time. 

Right.

On the day you are to sign up for freshman classes, the two of you pile together on your bed. It’s strange, almost, to think that you’ll be moved out of this room and into a dorm building in the next few months. One look at your skeleton friend, and you know he’s thinking the same sort of thing.

You and Rus both have to take a Magic-Biology class so you decide to get the same class time. It’ll be so much easier to tackle together. Thank the lord for core subjects. 

Unfortunately, though, your options are limited. Some of the classes are already full. Once you account for both that and the parts of your schedules you’ve already picked out, there’s only one slot that works for the both of you.

It’s a ten a.m., three days a week, taught by a Dr. W.D. Gaster. 

His rating online is... intimidating. Everyone says he's a hardass, that his tests are hell and he's kind of pompous. You're looking at the ominous comments with worry in your eyes. Should you and Rus just settle for different class times with nicer professors? After you do a bit of scrolling, Rus nudges you away from the screen.

“it’ll be alright, hon,” the lanky skeleton says. “even if it’s a shit class, we’ll suffer together.”

There’s something oddly sweet about that statement. It reassures you enough to stick with the class. 

The summer passes without incident. If anything, it only makes you more and more eager for the first part of your adult life. Rus moves in a day after you do, but he’s still there to help you carry and rearrange things. 

The first day of college is a Monday, and you and Rus walk to your ten a.m. together. Dr. Gaster's class is in a rather large lecture hall, already abuzz with small talk. The two of you stride through the room five minutes early and sit right next to each other, near the middle. 

The room is cold. Your leg bounces incessantly. 

It’s almost as if Rus can sense your anxiety. “seriously, relax. it won’t be bad. we’ve got this.” His bony thumb ghosts over your arm, barely there but still comforting. You always appreciate his light touches. 

With a loud _tick_ , the stark-white analog clock stands at ten o'clock exactly. An anxious silence settles over the class.

Then a door at the front of the room opens, and out steps Dr. Gaster.

Your professor is, like Rus, a skeleton, standing taller than any human man. His skull is squarely-angled, almost like that of a human face, with two scars branching out from his sockets like cracks on a windshield. Even though monsters don’t typically show or measure age very obviously, he seems older. Perhaps if he were human, he’d be in his late forties. 

Nevertheless, he's _very_ attractive, though in a different manner than the way you find Rus attractive. He’s wearing a fitted turtleneck under his suit jacket, and everything is in greyscale. It’s a polished, classy look that you appreciate.

He steps to his podium in the lecture hall, footsteps tapping timely against the floor. A long, gloved hand reaches down to the mic to adjust it, giving it a few taps to ensure it’s on. 

And then he says, “Good morning,” and that voice is so deep and dark you could drown in it. 

_Oh dear god._

Rus taps your shoulder, leans in, and asks, “you okay? lookin’ a bit scared over there, darlin’.” 

You’re not sure how to answer that. 

“Excuse me, young man,” Dr. Gaster’s voice interrupts your thoughts. When you look up at him, he’s staring Rus down. That glare is icy. “Are you speaking over me? In my own class, on the first day?” 

“shit, sorry,” Rus quickly defends himself.

Your professor only clicks his long, inky-colored tongue (that you _definitely_ aren’t ogling). 

“You’re paying for this class, so I suggest that you listen. Besides, I doubt that the lovely lady beside you would appreciate you distracting her.” 

He looks at you and smiles. 

In the seat next to you, Rus feels white-hot jealousy bubbling up inside of him. 

It’s all downhill from there, frankly. The class isn’t that hard for you, much to your surprise. You speak actively and take notes diligently. You’re always there, too. Every time Rus suggests skipping, you merely grab him by the hand and drag him to class. 

Dr. Gaster seems to appreciate your efforts immensely. He calls on you frequently, and when you get especially emphatic about an answer you see a trace of a very dark smile on his skull. A look like that never fails to make you flush in that lecture hall. He’s handsome, too handsome. Some days you can’t think straight, and yet, you’re doing impeccably.

You get your first exam back and you’re thrilled with the high B you made. It’s especially pride-inducing when you realize that most of the class failed.

Rus included. 

You’re baffled when he lets you see his grade. 

“How in the world…” you ask. The two of you did all of your studying together, and he’s been to every class, just like you have. How could he put in the same amount of effort and get such awful results? Rus isn’t stupid, not by a long shot.

The lanky skeleton’s convinced that Gaster has it out for him, and you’re not disagreeing. When you go over the exams in class the next day, Rus lets you see his copy. His questions are… harder? They cover roughly the same material, but the phrasing is so much more complex, and so much more difficult to understand. Sentences swirl and loop around each other. It takes you several minutes to understand what they’re even asking. There are some questions your friend didn’t even answer, they were so difficult.

“Go talk to him after class,” you whisper from your desk. “This is _ridiculous_.” 

“nah,” he replies, raspy voice low. “i got somethin’ better."

You can only fix him with wide, bewildered eyes as he raises his hand. 

Seeing the motion, Dr. Gaster turns in your direction. “Yes, Rus? May I help you?”

“uh, yeah, what the fuck is this?” He’s got his test gripped tight in his phalanges, holding it up next to him while he stands. 

“Rus,” you stage-whisper, giving him as serious of a side-eye as you can manage from your seat next to him, “What the fuck are you doing? Sit _down_!”

He ignores you. Gaster glares him down. 

“What do you mean?” Your professor contests. “If you’d like to discuss your grade, Rus, you may do so after class.” 

Your friend only snorts through his nasal ridge. “nah, i’d like to discuss you. i'm callin’ bullshit.” 

You’re not oblivious to the way Dr. Gaster grits his teeth, malleable mouth curling into an irate sneer. 

“On what, exactly?” 

_“you.”_

“Pardon?” Though he’s asking for clarification, you can tell he doesn’t need it. It’s an out. _Back down, Rus. Please._

Of course, he doesn’t. He spits it. “i said, you’re fuckin’ bullshit. it’s all you are."

You can hardly get out an “Oh my god, Rus,” before Gaster begins to step closer, closer to where you’re sitting together, as close as he can get. There’s no sound in the air but the precise, evenly-timed clicking of his shoes against the tile. Only a few tables serve to separate him and Rus, and you’re so thankful for them. You’re not even the subject of his anger and yet you’re still trying to shrink into your chair. The sneer’s worsened. You can see every meticulous point of his perfect teeth. Dr. Gaster’s eyes burn into Rus, molten hot blackness, dark and getting darker still. 

The worst part is how steady he still sounds. At the sharp edges of his voice is a cold hiss. “You _dare_ to disrespect _me_ in _my own class_? To _embarrass_ me like a damned _fool_? It seems you’re more of an _idiot_ than I perceived.”

Rus opens his mouth, but he’s cut off.

“Be surprised if you pass, you incorrigible nuisance of a boy,” Dr. Gaster snarls, and then turns on his heel and walks away. 

All you can do is put a comforting arm around Rus and try to ignore the burning between your legs. 

The instant you get out of class, you whirl on your best friend. “Rus, what the hell?!” Your hands find his shoulders and squeeze hard. His jacket’s soft.

“had to call him out somehow. that’s all i’m gonna do. worst-case scenario, now everyone knows he’s a fuckin’ ass.”

“An ass?” You ask. “He looked like he was going to fucking kill you! Holy shit, and that thing he said about failing?”

“empty threats, hon, empty threats,” he waves a bony hand off to the side as you walk together. 

You sigh. “Rus, he scared me.” You’re not going to mention what _else_ Dr. Gaster makes you feel, especially not after what just happened. Not a good time.

But Rus coughs out a dry laugh. “you’re the last person who should be scared of him. you’ve got the perfect grades, you’re always talking, and oh, he definitely wants to _bone_ you.”

“What?” You snap your head in his direction. What?

“uh, is this one of those times where you want validation, or do you really not notice how he looks at you _every damn day_?” 

No, you've seen the looks, those sly smirks and intense gazes, but they’re always directed at the class in general, right? And even if they _were_ directed at you, they don’t mean… do they? 

Rus seems to notice your internal crisis, because he stops and pulls you to the side. There’s a bench by the sidewalk, and with both his hands he plops you down on it. The wood creaks when he sits down next to you.

“darlin. relax,” Rus tells you. “don’t worry about it. don’t worry about _him_. i can handle this.”

But can he? He’s been struggling with every assignment so far, and Dr. Gaster _certainly_ isn’t making things any easier on him. What happened in class was _intense_. Almost one half of the semester is already over, and aside from the stunt he just pulled, you have a hunch that Rus isn’t going to do anything else about his grades or the class. That’s how he typically “handles things,” anyway. 

_”Be surprised if you pass,”_ Dr. Gaster told Rus. Given how straight-forward he’s been, you don’t doubt that he meant it. The thought’s terrifying. An F on Rus’ transcript already? He’s got to keep his scholarship. He can’t flunk out, he’s too smart, too kind. This isn’t fair.

You aren’t going to let your best friend fail while you have an A. Surely there’s something you can do. 

When you get back to your room later, you look up Gaster’s office hours, and learn that he does appointments by phone. Oof, you’ve always hated making calls. Nevertheless, though, you work up the courage, suck in a breath, and dial the number your professor listed.

Ring. Ring. What will you do if it goes to voicemail? Ring.

“Yes?” The voice that answers is smooth, too smooth. You’re feeling warm again. 

You try not to let your voice squeak. “Dr. Gaster? It’s _____, from your 10 a.m. magic-biology?”

“Ah, yes, my star student.” Something about that phrasing sends shudders through your whole body. “What do you need, dear?”

_What do you need?_ There are a lot of answers to that question, especially when coming from him. You need to figure out what’s happening with Rus’ grade. You need to see what you can do to help him. You need to know if your professor wants to...

You take a deep breath, and then say into the phone, “Can we meet?”

You don’t tell Rus, not a damn thing. Two days later, you get up and fish that little black skater dress from the back of your closet. You pair it with cute knee-highs. There, it’s dressy, but not over-the-top. A spritz of your favorite perfume wouldn’t hurt, either. 

Office hours are right after class, and you’ve got the first slot. You can do this. You’ll do it for Rus. You’re antsy the whole time, though, and it doesn’t help that your best friend is suspicious. 

“what’s with the dress, hon?” He asks as you meet to walk to class. You watch those low, lidded eyes travel up and down your body. His gaze is a welcome one, with familiar warmth behind it. “not that ‘m complainin, makes you look super cute. but still, you got a date or somethin’?” 

“Pfffft, no,” you snort, laughing it off. “Just felt like it today.” 

He doesn’t pry any more, but you don’t miss the way he keeps stealing glances at you. 

If that weren’t enough, there’s also the fact that Dr. Gaster is _most definitely_ staring at you during class.

He’s subtle about it, sure, but you can’t overlook the way that intense violet gaze keeps flicking over to your seat. It makes you heat up all over in a way that’s not exactly unwelcome. It’s a struggle to not squirm in your seat.

_Don’t freak out now. This is normal. Rus said he normally stared at you all the time in class. Maybe this is just the first time you’re noticing it. It probably doesn’t even mean anything. He’s waiting for you to raise your hand to talk again, or he wants to know what you think about the lecture. Maybe today he’s wondering about the meeting. The meeting isn’t even a big deal, either. You’re just going to talk to him and kindly convince him to lighten up on Rus somehow. If you’re polite, and well-mannered, and persuasive enough, you can probably make some progress._

Rus pulled quite the stunt last class, though. How in the world are you going to persuade Dr. Gaster to forgive _that_?

Class gets out, and you run into your next problem when Rus starts talking about grabbing lunch. 

“…there’s the cafeteria, that’s an idea. or there’s the burger joint across the way, i know you love their cheese sticks, or-"

“Actually,” you butt in, “I, um, I have to run an errand and it’s not something I can really put off. If you still want we can get food after I’m done!” 

Raised sockets and a contemplative frown. Yeah, no, he doesn’t buy that at all. He knows you too well, and at the very least enough to grasp when you’re lying to him. 

But all he says is, “alright. whatever you say. i’ll, uh, i guess i’ll text you then. see you around, hon.” The smile he gives you is too forced. 

You feel bad, but you know that if he knew he wouldn’t let you go. He already can’t stand Gaster to begin with, that much is obvious. And then there’s how you're dressed, and then there’s the possibility that your professor wants _something else_ from you… Your best friend would have a stroke if he knew where you were going and what you were doing.

So you watch him go, and when he’s several steps away you turn and make your way towards the concrete building across the block. Your meeting’s in just a few minutes. At this pace, you’ll be right on time.

Rus at least lets your figure get a good way down the street before following you.

Dr. Gaster has an office all to himself. You stand outside the door for a few moments, just taking some breaths. You’ve never spoken to him one-on-one before, or at least not without an audience. It’ll be fine, you tell yourself. You’re his… star student. That’s what he called you, though the underlying tone of that was and is questionable. He likes you, or at least appreciates you. You’ll be fine. The door looks unlocked, but you knock anyway.

“Come in.” That voice seems even deeper when it’s not echoing off the walls of a lecture hall. It pulls you through the door and into your professor’s office. 

Gaster’s sitting behind his desk in a very comfortable-looking chair. There’s an ice-filled glass of some amber liquid on a coaster in front of him, and you have a feeling it’s neither Coke nor Pepsi. How did he manage to get so settled in his office when class just ended?

You’re a little intimidated. Okay, extremely intimidated. 

“Good afternoon, _____. Please, take a seat, make yourself comfortable.” 

Your throat’s going dry and your body’s heating up. You sit. 

Gaster says, “By the way, you do look quite nice today. It’s a lovely change from those tight leggings you seem to enjoy.” 

Are they tight enough for him to notice? Does he notice? Does he stare when you aren’t looking? Rus seems to think he stares. Your face is getting warmer.

“Thank you, sir,” you stammer. He seems to like that, and smiles. Oh, that expression. “But anyway,” you continue, “I’m here to discuss something with you.” 

He clicks his tongue, gaze level with yours. “This is about Rus, is it not?” It’s not a question. He already knows why you’ve come to him. 

You nod. “Look, Dr. Gaster, he’s my best friend. We do everything together. We signed up for this class together, take notes together, and do all of our studying together. It doesn’t explain why I have an A and he’s nearly failing. It doesn’t add up.” 

“A correct assumption,” he remarks. 

“And then there was what happened the other day in class. Sure, Rus started the ruckus, but you seemed to spur him on and encourage his behavior. You built it up until it was reasonable for you to lash out at him and threaten his grade,” you reason aloud. It’s taken a while for you to process it all, but now that you have, you feel like it’s coherent.

“What are you getting at?” Gaster asks. He’s got one elbow propped on the mahogany, peering at you inquisitively. There’s a darkness to his voice that only intensifies the heat in the room. 

Is it the room, or is it you? 

But then you lean forward on the desk. You’re probably going to regret being this forward. “What I’m getting at is that I notice how you treat him. I think you’re giving him a hard time on purpose. You want an excuse to fail him.” 

And it’s out there.

His smirk is almost predatory. It’s terrifying (exhilarating). “Such a bold conclusion, my dear.”

A beat of silence, a beat of tension. Your skirt’s too tight. You narrow your eyes and lean closer.

Gaster says, “And it is a correct one. But why wouldn’t I challenge Rus? He’s blatantly rude, disrespects me at every turn, and then he distracts *you* from *your* education. Come now, don’t you see that he hinders you?”

“I don’t see that at all.”

He seems almost amused by your curt reply. “Nevertheless, his massively-inflated ego could afford to be knocked down several notches.” 

“You’ve knocked him down enough, I’d say,” you remark.

“My, my, are we talking back?” He sips his drink (you think it’s scotch or whiskey of some sort) but he keeps his eyes trained on you the whole time. You watch him swallow the liquor without the slightest change to his expression.

“For my friend, I would.” 

He stops a moment to laugh a little, haughty silk coming out his jaws. “That’s the second time you’ve used the word ‘friend’ to describe him. My dear, you’re so intelligent; do you really not see how much he adores you?” 

You fix him with furrowed eyebrows and a flatlined mouth. He continues.

“Frankly, I’m surprised you aren’t out wearing that little dress for him instead. A beautiful woman like yourself deserves that kind of attention he wants to give. That boy looks like a starved animal in class, he’s so desperate for you. It’s almost tragic how funny it is.” 

Rus… likes you? Enough for Gaster to notice? And you’re… beautiful?

But Rus said that _Gaster_ was the one that liked you. 

“What-“

“But never mind that,” Dr. Gaster brushes off the topic with a wave of his hand. “I’d like to know why _you_ , lovely girl, are here on his behalf.”

Another beat. You’re shaking, struggling to keep your cool in a room that’s so hot, with a man that’s making you hot on the inside. If he calls you lovely or dear one more time, you just might keel over. 

He prompts, “Or is there perhaps another reason you’re here instead?” 

The implications are clear. They’re crystalline, with that gaze of his. You haven’t been blind to the way it’s been traveling up and down your body slowly, like you’re a meal he’s savoring. He could eat you alive, devour you and leave a wanton mess in the wake of your body.

You’re trying to get your composure, but your voice keeps shaking. “I’m- I’m here for Rus, to help him, but also I…"

Shaking fingers curl around the hem of your little dress. Your breath catches in your throat. Are you really about to…

Are you going to act like you don’t want to?

You hitch your skirt up, just enough, and lift one of your knees until it’s up and flush on his desk.

“I think I know how to appease you, sir.” 

He looks pleased already, that wicked grin widening across Gaster’s scarred skull. After taking another sip of his drink, he pats the condensation off of his gloved hands onto his slacks.

“Ah, I was wondering when you would breach this. Brave girl.” 

And then his voice drops to something even deeper, and that refined cadence now has a razor-sharp edge to it.

“You can start by crawling to me.”

  



	2. No I in Threesome

**Summary for the Chapter:**

> Let's Crawl, Y'all.

**Notes for the Chapter:**

> Although the chapter is titled after a really good Interpol song, the vibe is definitely more "Skin" by Rihanna. So there's your mood music because it's about to get nasty.

  


And crawl you will. 

So you flip your hair to one side, look him in the eyes, and do exactly what Dr. Gaster’s asked. It’s a strange thing to do on a desk, crawling, but his is sturdy enough that you don’t worry about falling or breaking it. As you move you arch your back, putting a bit of a swing into your hips. Might as well give him a show. 

You crawl slowly, shifting your weight from your knees to the heels of your palms, and watch him watch you. It’s utterly thrilling to have those deep violet eye-lights fixated on you so intently. When you reach the other end of the desk, your faces are close enough to touch. Warmth shoots through your body. 

He’s still got his gloves on as he cups your jaw. The silk grazes your cheeks and you feel how soft is is against your skin. 

But then his gaze flicks down to your shaking legs.

He says, “You do know that if you’re nervous, you don’t have to go through with this, correct? If you’re feeling the slightest bit hesitant, you can walk right out that door and I would never tell a soul.”

“I know,” you say. You don’t budge an inch, not even to look over your shoulder at the door. You’re nervous, surely, but that certainly doesn’t mean you’re second-guessing yourself, or that you want to leave.

"My dear, are you sure this is what you want?” His gaze grows even more inquisitive. “All for your friend?”

You take a breath and answer, “Yes sir.” With a smirk, you add, "And maybe a bit for myself.” 

“Very well,” Gaster says, and hungrily closes the gap between your mouths.

He possesses a skill you wouldn’t expect from a skeleton monster. Though he lacks lips, the area around his jaw (mouth?) is still soft, still malleable enough to press and groove against you with precision. 

The fingers that were cupping your jaw are trailing down your neck, leaving behind a kind of electricity that you get addicted to in a matter of seconds. Every caress, every brush of his smooth tongue against your lips, it’s all remarkable. He tastes like nothing and everything all at once. 

Amidst the heat of the kiss, you wish you had done this sooner; his lingering stares made it oh-so-tempting, but you weren’t sure how to approach it. Now, though, you have.

For Rus. 

Rus. 

You relax in Dr. Gaster’s grip. You’re moved to sit on the edge of the desk, legs dangling over the end. Soon enough, you feel hands on your thighs. The tips of his fingers drag over your dress hem slowly, as if he’s savoring every moment he touches the polyester.

His mouth moves to leave kisses down your neck, and his deep voice is still calm as ever when he asks, “My dear, you’re not afraid of anyone catching you? Catching… us? Together?” 

His breath ghosts over your throat. Each kiss is feather-light, but he grips your legs so steadily you know it’s all methodical. It feels absolutely heavenly and makes your eyes flutter.

You manage to shake your head and reply, “Nobody will see this. Nobody knew I was coming here, and I made sure I was alone when I walked over.” 

“That’s a smart girl.” Gaster nods before meeting your lips again for a deep kiss. He stands this time, towering over you, with one hand tilting your chin up and the other trailing up your thigh. He grazes the tops of your socks, humming in appreciation. Does he… have a thing for thigh-highs?

You suppose you’ll ask him when he isn’t slipping you his tongue and caressing his way inside your dress. That seems more important at the moment. 

That hand is sliding up the inside of your thigh, softly but not quite gently. You remember he’s still wearing gloves when he brushes right up against your underwear. The lace catches on the silk, and you shudder against the friction.

Then, though, you feel Gaster's hand moving higher up, to your hips where the waistband of your panties sits. The hand on your neck ventures down and under your dress as well. The fingers from both sets of hands hook around the lace. You lean up to kiss him harder, and he pulls. Your panties come up your legs slowly, and when he slides them over your heels and off, you realize you’re exposed to him. 

Dr. Gaster grins and says, “You look utterly divine.”

“Thank you,” you manage to squeak, blushing under his stare. 

You’re not expecting him to immediately move his hand back to your pussy. He rubs you slowly, teasingly with only one finger. The soft fabric slides up and over your clit where the heat’s bundled itself. He barely grazes you and you let out a breathy moan. You only get louder when he adds more pressure, nearly dipping his finger into you.

“Hm, and you’re soaked, too, aren’t you, my dear?” He teases, the smugness evident in his voice. 

You watch him withdraw his finger, and anticipating his movements you catch his gloved hand on the way to his mouth and move it to yours instead. Making sure to look him in the sockets, you take his finger in your mouth and suck. You can taste yourself on his gloves. What’s even better, though, is when you run your tongue up his digit and hear the choked moan in his throat. 

When he pulls his finger out of your mouth and removes his gloves from both hands, you start giggling. That doesn’t last very long, though, before he grips your throat and pulls you back up to kiss him. His mouth is hot, almost burning with raw want.

“So sweet,” he remarks, inky tongue running over his own mouth. 

Gaster steps away and sits back in his chair, merely staring at you once again. You feel like you’re being studied, but can’t help but enjoy your exposure with a flushed face. With the skirt of your dress bunched at your waist, and your legs spread, he only has to lean down a bit for his face to be between your thighs. 

That dark look in his eyes tells you he’s thinking the same thing. He leans forward, giving you that black, hungry gaze and that heated smile.

You’re anticipating that first lick when the door busts open.

Oh _fuck_. 

_You should’ve locked the door. Why didn’t you lock the fucking door?_

You’re frantically springing up from the desk, swiping your dress down in an attempt to smooth it, and trying to think of some legitimate story about why you were on Dr. Gaster’s desk to tell this stranger when you notice that your professor doesn’t seem panicked at all. 

In fact, he seems rather amused. Wondering why he’s smirking, you turn around to be faced with your best friend of all people. He’s right by the now-closed door, stock-still with his russet eye-lights on you. You notice the tension in his squared shoulders. 

“Good afternoon, Rus. I was wondering when you would work up the nerve to walk in,” Gaster greets him, and all you can do is gape. 

Just how much did Rus see? 

And why is he here? Why was he _watching this_?

Rus speaks up, his typically-raspy voice a loud, angry warble. “fuckin’ seriously? jesus, gaster, i knew you were an asshole, but a fuckin’ scumbag? taking advantage of _____ like this?” 

Gaster arches a socket. “That’s peculiar phrasing, Rus. Does she look like she’s being _taken advantage of_? Does it appear as if I coerced her into anything?”

“well-“ He starts to answer, but he’s cut off.

“ _Well_ , if you were observing from the beginning of the meeting, you would know that _____ was actually the one who propositioned _me_."

Rus fixes you with betrayed eyes, wordless, and you start to wonder if this really was a good idea after all. 

You better explain yourself, or at least try to.

“Hold on, Rus, there’s- it’s just- I…” You’re stammering, but it’s better than nothing. “I came here for you- you know, you were going to fail, and I hoped I could talk some sense into Gaster so he’d- and then there’s that thing you said, about him and- him and me, and him looking at me, and-“ 

“and you were gonna fuck him to get me a better grade?” He finishes, and you wince.

You squeak out, “I was trying to help you.” 

“seems to me like you were looking for an excuse,” he counters.

You feel the hot sting of his words spread through your chest and go quiet. Leaning against Dr. Gaster’s desk, your eyes find the dark-colored carpet. If you look up at anyone, at either of them, then they’ll know how right Rus is. 

Unbelievable. Even your best intentions blow back up in your face. This was a mistake, you shouldn’t have done this, shouldn’t have even _considered_...

Gaster interrupts the silence with, “Oh, a little quarrel. How cute.” 

You whip around to face the man who still holds your lace panties in one hand. “Cute? My best friend is _angry_ at me.” 

Your professor only counters, “Angry? I’d say _jealous_ would serve to fit a better description for the young man. That’s all this is: an act of envy.” 

You manage to look over at Rus again, and you notice what you once perceived as malice is more akin to pain. The narrowed sockets are softer at the edges, pulled down a bit at the corners. Though his teeth are gritted together, there’s too much pressure, as if it’s being forced. 

“Rus…” you sigh. Something compels you to step forward and try to touch him, and surprisingly, he lets you. Your fingers lock around his skinny phalanges. He holds on. You look up at him.

Then the deep voice behind you says, “How can you possibly look at that face and question whether or not he’s madly in love with you?”

 _This again?_ You whirl around to face your professor and say, “You know, now probably isn’t the best time for this.”

“Oh, I think it’s the _perfect_ time,” Gaster says, and with that he tosses your underwear to Rus. Your best friend catches them before it seems he even processes what he’s catching. From a few steps away you watch him rub your panties between his fingers. The joints between each bone snag on the lace, but he doesn’t seem to mind.

From behind you, your hand’s grabbed, and you’re pulled back to the edge of the desk. An particularly hot wave rushes through you; despite being interrupted a few minutes ago, and despite the drama, you still feel the warmth and arousal you did earlier.

Gaster says, “Pardon me for thinking with my cock, but Rus, if you ever wanted a more blatant opportunity to show _____ your feelings, I wouldn’t be opposed to you doing so now.” 

You speak up to ask, “Wait, Rus, do you even-“

“uh… i think?” He interrupts, too quickly, and his skull’s flushed. "i mean, i’ve thought about this- y’know, with you and me- just hypothetically, obviously, and sometimes it’s more than just, y’know, fucking, and-“

Gaster says to Rus, “You’re beating around the bush. How could you not love her? She’s intelligent, focused, kind, and _very_ beautiful. Perhaps now you’d like a better view of what you’re so enamored with?” 

“uh, ye-“ 

You’re lifted back up onto the desk, and you don’t even object when your legs are spread back open and the fabric of your tight dress rides nearly up to your hips. In fact, the heat that never left you surges back through your body. From Dr. Gaster’s desk you watch two gazes fix themselves on your body: your flushed cheeks, the curves of both your legs, and the wetness where they meet. The room’s somehow tighter, hotter.

And then your dress is lifted off of you, leaving you completely naked.

Rus’ jaw looks like it’s going to detach from his skeleton and drop to the floor. 

“Utterly intoxicating,” Dr. Gaster says.

“fuckin’... goddamn,” your best friend breathes. 

Gaster chuckles, deep and dark. “Ah, see. I knew you’d agree. What a divine little creature she is, isn’t she? How could you _not_ fantasize about her?”

“holy fuck,” Rus breathes, and then the lights in his sockets meet your eyes, and it’s as if he’s just now realizing he can speak to you. “____, you’re beautiful, _holy fuck_.” 

“And so enticing, too. You could walk up to her and bury yourself inside of her _right now_ ,” Gaster says. It’s almost taunting.

You’re so quiet when you breathe out a, “Please,” but the smirks you get in response let you know they both heard. 

“Or her mouth,” Gaster counters. “And I certainly don’t mind sharing.” With a slender hand he guides you to lie on your back on the desk, your body hanging off either edge. With your head upside-down and facing the other wall, you can’t see either of them. The idea of not knowing what’s going to happen, not being completely aware, sends a shiver down your form.

Rus steps forward, around the desk, closer to you, and the familiarity he brings with him calms your shakes, even if just a little bit. The circumstances are still so strange, especially with the assumptions your professor’s made. You’re face-to-crotch with your best friend, your best friend who has… feelings? 

He kneels, and your eyes meet the rust-toned lights in his sockets. You use your gaze to question him.

His sigh is so heavy, like he’s been carrying it for too long. “_____, i-”

“Me too,” you cut him off, and before you can say anything else he kisses you. His bony hands feel firm on your face, but his touch isn’t harsh. It’s gentle, but it’s so needy at the same time. His tongue sweeps over your lips, and he tastes earthy, tangy.

You’ll worry about all the ridiculous semantics of this situation later, you decide, and melt against his kiss with a renewed sense of comfort.

Gaster’s been running his fingers up your thighs, but now he steps between them. You don’t need to see to know he’s absolutely towering over you. His hands take hold on your hips and he leans down so that you can feel his scarred, angular skull against your chest. 

His warm tongue grazes one of your nipples and you squirm. It’s so slender, and long enough for him to run it up the underside of one of your tits and over. He flicks his tongue over your nipple, then traps it between his teeth, barely biting down on you.

You moan against Rus’ mouth, and his teeth catch on your lips, making you whimper even more.

“you like that, darlin’?” He whispers, and all you can hum out is a “mm” as you go in for another feverish kiss. 

You hear the clink of a belt buckle, but it’s not Rus’. His hands are still holding onto your face, slipping through your hair.

But then your best friend’s murmuring against your mouth, “can i- i mean, can you- fuck, i mean, if you want to…” When his phalanges drag over your lips, you understand what he wants, and nod.

Rus stands up, slides his shirt off, and unbuttons those skinny jeans that you’ve always eyed. They look good on him, but you’re burning to see them slip down his legs. They drop to his ankles, and his boxers go with them. You’re about to giggle about how silly he looks with his pants down, but then he takes them off entirely, and it’s only then that you notice his cock.

His cock’s right at your lips, the same burnt red color as his eyelights. He’s long, but not super thin, and you take his head into your mouth without any trouble. The grunt that comes out of his jaws is enough to make you moan yourself. You sweep your tongue over his shaft, earning a groan.

“fuck, how are you so good…”

At the same time, Gaster’s shirt drags down your stomach as he kneels between your legs. You let out a hum of satisfaction, more than ready to resume what was interrupted earlier. His arms are bony, but they feel strong as they wrap around your thighs. He kisses your thighs, almost endearingly, but it still has you soaked. With two phalanges he spreads you open and licks you, long and slow and teasing, all the way up your slit. 

_Oh god_ , you want to moan out, but your mouth’s so full. Rus thrusts into your mouth faster, muffling your noises even further. One of his hands wraps loosely around your neck, keeping hold on you as he fucks your mouth.

“you’re so fuckin’ pretty with your mouth around my cock,” he murmurs, urging you to take his entire length down your throat. He’s so long that you worry you’ll gag, but you’re grateful to yourself when you don’t.

“Hm, and you taste _divine_ ,” your professor remarks from between your thighs.

Gaster lashes your clit with his tongue, almost merciless with his touches. He pulls you closer with his hold on your legs, face pressing into your pussy. He laps at you as if he’s a man starved, but with the precision of one who knows exactly what he’s doing to you.

He groans against your body, his phalanges digging into your thighs as he grips them. His tongue is wet and silky and so fucking _skilled_ that you can’t stop moaning over your best friend’s dick.

With the hand that’s not around your neck, Rus grabs at one of your breasts, squeezing you in his fingers. While he squeezes your throat tighter, he sweeps a bony thumb over your nipple. You shudder, and he smirks. 

“feel good, darlin’?” Rus asks as he pinches a nipple between two phalanges, sending the smallest wave of pain through your body. 

It’s enough, though, with all the heat and the pleasure building up in your body. You cum squirming on your professor’s desk with his tongue on your cunt and with your mouth full of Rus’ cock. It’s the most intense thing you’ve ever felt, utterly electrifying. You can feel other objects on the desk shaking from the aftermath.

“Oh my god…” you whisper, as soon as your mouth is free. Rus has since pulled out of your mouth, and is running gentle hands across your body as you breathe. 

“yeah?” he whispers, “was that good, sugar?” His voice is husky, rawer-sounding than normal as he caresses from your shoulders to your chest. Your fluttering eyes and shaky nod gives him enough of an answer that you don’t quite have to verbalize for him. 

You’re still so sensitive when Dr. Gaster decides to thrust into your pussy. 

You’re not expecting it, though, and the loud gasp you let out informs both skeletons of the fact. 

Gaster’s voice is thick and heavy when he asks, “My dear, are you alright?” 

“Mhm,” you moan out, “you’re just so…” _Thick. Long. Powerful. Rubbing you in all the right ways. Making your toes curl._ You can feel your body squeezing his cock, and he’s not even hilted yet. You can’t even finish your sentence, it feels so good. You can’t _stop_ clenching around him, and as he grips you even he shudders.

You decide to look up, out of curiosity, and tilt your head up enough so that you can lean it back against Rus’ ribs. He strokes your hair gently, tugging it a little, while working his other hand over his still-hard cock. You replace his hand with yours, squeezing him as you stroke him in your fist.

“f-fuck,” he groans, bucking into your hand. “you feel so fuckin’ good, hon.” You look back for a moment to meet his burning eyes and the rough passion within them, and then with a shuddering gasp turn your gaze back to between your legs. It’s been so hard to divert your attention away, with how your professor’s cock has been stretching you.

Gaster’s sockets are nearly black as he hilts himself in your pussy, his massive hands gripping your hips. “You beautiful little minx,” he growls at you, body heaving, tie undone, nearly mad with desire. “I’m going to tear this precious body of yours in half.” 

His words send shockwaves through your form, and his cock fills you to the brim. 

Your professor all but yanks his tie off and hastily unbuttons his dress shirt, leaving the clothes to pool on the office floor with reckless abandon. His body’s not too different than Rus’, other than being broader in the chest, shoulders, and hips. You watch him pull out, and in the moment before he thrusts back into you your eyes widen at the sight of his cock. It’s a dark indigo color, smooth, and so big you can’t even fathom how he’s _fitting_ inside you. 

He thrusts in all the way again and your entire body trembles. “Ah,” you gasp, unable to hold back a moan as you squeeze Rus’ cock harder. You pump him faster in your hand and arch to look up at him with widened eyes. He’s so handsome, truly, in a way you could’ve never imagined before this. Rus leans down, bending at the waist to crash his mouth against yours. You kiss him rougher this time and try to keep still, though it’s hard when Dr. Gaster’s fucking you so thoroughly. 

Your best friend’s hand reaches down your body and between your legs, making you gasp as he uses a phalange to rub your clit slowly, gently. You cry out more, shaking and arching against him even more. 

Gaster takes a moment to adjust his grip on you, body still heaving and cock still throbbing. When you watch him move your legs so they’re up on his statute shoulders, you just _know_ he’s going to hit all the spots you need to cum a second time. You’re already so close as is, and by the carnal smirk on his skull he seems to know that. 

However, you’re further up on the desk, so Rus has had to readjust, opting to walk around to the other side near where Gaster’s standing to run his hands up your body with easier access. His touches are so light and playful, yet so tantalizing that it merely adds to the heat pooling at your core. 

Dr. Gaster seems to take his sweet time in entering you again, slowly caressing over the hems of your knee-high socks as he eases into you again. This is almost more torturous than the pace he was working at earlier, as you can feel the thickness of his cock dragging against you ever-so-slowly, and it just feels so _delicious_ that your eyes roll back a little. 

“what’s that, darlin’?” Rus teases, moving his focus to your nipples, “does that make you wanna cum?”

When you whimper out, “Mhm!” you expect to be thrusted into oblivion and given what your body is absolutely begging for. However, instead, Rus grabs a fistful of your hair and pulls the top half of your body up, with the rest of your weight in Dr. Gaster’s arms as he fucks you. 

“not yet, hon,” Rus chides you teasingly, “we’re not ready for you to cum again just yet.” You whimper at his admonishment, clearly not expecting such an order from him of all people. He and your professor exchange the briefest of smirks, an unspoken communication between the two of them that fills you with an exciting sort of anxiety. 

He pulls your face closer to his to kiss you roughly, his teeth digging into your lips. Your arms wrap around him for leverage as Gaster slowly drives himself into you again. Rus squeezes one of your tits in his free hand, making you moan even more. 

Then, his hand starts to drift lower and lower on your body, and you’re wondering what’s coming next when you feel his touch against your ass. His phalanges gently circle your asshole, prodding with the most gentlest pressure. He rubs you slowly, giving your body time to relax and adjust to the new sensation. You gasp against his mouth, anticipating the feeling of his fingers pushing inside you. 

“you want it, sugar?” Rus rasps against your lips. His voice makes you quiver in his grip as you nod. 

However, before you can even focus on the feeling, Dr. Gaster grips your hair and pulls you back towards him. He crushes his mouth against yours in a hungry, needy kiss as he grabs a fistful of your hair, right at the crown. His cock still feels massive inside you, even as he thrusts so slowly and sensually. Every dragging thrust into your cunt and powerful tug at your hair sends heat through your entire system. You have no idea how you haven’t come undone yet; it’s near-impossible to hold yourself back like this. Absolutely helpless to the way your professor’s fucking you, you moan into his mouth. 

Rus slowly pumps a phalange into your ass and you whimper even more. The finger pushes into you gently, stretching you in the slightest, but most electrifying way as you now have two holes filled. You grip onto Rus even tighter as he inserts a second finger, and break your kiss with Gaster to look at your best friend longingly. You’re squeezing his phalanges so tightly, and as he leans forward to kiss your neck there’s a subtle smirk on his skull.

“does that feel good, darlin’? you want more?” he murmurs against your ear.

In response you squeak out a “Please!” 

The lanky skeleton only smirks wider as he scissors his fingers, stretching you wider. Dr. Gaster picks up the pace, quickening his thrust enough to make your toes curl in your socks. He pulls your hair harder, making you arch back and clench around both his cock and Rus’ fingers.

Rus murmurs, “then cum for us,”

“Right now,” Gaster adds, and the intensity in both their voices are just enough to send you over the edge. You cum squirming on your professor’s cock with your best friend fingering your ass. Your entire body shakes, and you have to grab onto both skeletons to properly steady yourself. The noises you make as you climax are driving them wild, if their heavy-lidded expressions are any indication.

“Yes, that’s it,” the former coos at you, petting your hair that he was pulling just moments ago. “You look so beautiful cumming on _my_ cock, dear.” He looks so smug, and that pointed tone clearly rubs Rus the wrong way. Your friend rolls his eyes and takes hold of your waist, a touch of mischief tugging at his grin.

“then i think it’s my turn,” he comments, and moves to pull you closer. Dr. Gaster pulls out of you slowly, hissing in pleasure as his cock rubs against your walls soaked in your release. The both of you can’t help but sigh when he’s fully out of you, and you whine at the feeling of emptiness. Nevertheless, you follow Rus’ lead to hop off the desk. He places two bony hands on your face and kisses you with an intensity you certainly weren’t expecting from him. He’s always been so laid-back to you, so effortless and gentle, but the way he’s been ever since barging in on you and your professor has you thinking that perhaps you waited too long to start something like this with him.

“this is..” he murmurs against your lips.

“...fucking awesome?” you finish for him, breathless from both his kiss and your second orgasm. He huffs out a laugh, and you feel something inside you swell because you realize that his laugh is suddenly so sexy to you. 

Meanwhile, Dr. Gaster is positioning himself on the desk instead. He’s far too tall to completely lay down on it, so his legs hang off the edge. However, once you turn to look at him, with your eyes meeting his pitch-dark ones, you think you understand what he’s getting at. You walk over to the desk, regarding his body with a lingering gaze, because he truly is beautiful, in the most polished, masculine way. Your body wasn’t mistaken in the slightest when you first saw him and were instantly drawn to his powerful elegance. You’re not sure if you could ever look at him any differently after today…

but you don’t think you want to.

So you don’t hesitate to lean back on the desk, and sure enough, his hands grab hold of you to draw you against his chest. Your head’s cradled in the crook of his clavicle, and surprisingly, he’s comfortable to lay against. He leaves lingering touches all over your body as he traces your figure with his fingers. 

Rus stands at the edge of the desk, regarding you with a curious, but still amused gaze. In response, you don’t say a word, but instead slowly spread your legs open for him. You make a bit of a show of it, revealing yourself like he hasn’t already seen your pussy just a few minutes ago. It seems to do something to him, because in his spot he shudders just looking at you, rust-toned cock throbbing at the sight of you. 

“Aren’t you just divine?” Gaster comments, mouth against your ear, and you can feel his wicked grin. His hands run up your body again, pressing against each and every curve until they settle at your breasts. He moves one hand back down, to position his cock at the entrance to your ass. You can feel how wet his cock is from being inside your cunt, and you’re already prepped and ready from Rus’ fingers. 

Rus, at the same time, is lining himself up between your legs. His cock slips against your still-wet slit, the head nearly sliding in already, and he holds back a grunt. You can tell he’s trying to take this slowly and savor it by the way he’s rutting over your pussy.

“fuck,” he sighs, shuddering, “i’m not even inside you yet and i already wanna-”

“Shh,” you hush your best friend, giving him a playful grin. You use your fingers to spread your lips open, showing off enough to punctuate your sigh when you say, “Just fuck me already. Please, Rus?” 

His hands quickly find tight purchase on your hips, and without any other hesitation Rus thrusts his cock into you. The both of you let out breathy moans at the same time, overcome with the heat between you. His cock feels so perfect in you, long and brushing against all the right spots so that you’re already crying out. He starts at a decent pace, with his phalanges wandering over your hip-bones and your thighs. You can’t help but moan every time he hilts himself.

Dr. Gaster murmurs into your ear, “You give quite the show, don’t you, you lovely little thing? I don’t think I can help myself much longer..” He presses a lingering kiss against your forehead as his cock nudges your ass. You feel him readjust himself under you ever-so-slightly, though he’s holding onto you so that you don’t shift along with him. His cock feels so big at your entrance, and even though it’s adequately lubed, you’re not sure how he’ll even fit. 

He pushes himself into you at an agonizingly slow pace, taking his time to even nudge his head inside of you. You start to quiver and squirm, already overcome by how full you feel with his gentle thrust in addition to Rus fucking you at the same time. In response to your anxious movements, your professor merely caresses your body up and down slowly. 

“Aren’t you just so perfect?” He coos to you, “I can’t even _fathom_ why I didn’t invite you here the first week I laid my eyes on you.” You can feel him thrusting his cock in further as he murmurs all those words that sound sweeter than honey tastes on your tongue. It’s the very thing that started this whole endeavor, that voice of his; it’s so deep you get lost in it, so deep it sparked your little crush on him. “You can take it all, can’t you, dear? That’s right, take my cock like a good girl…” He rasps, and then there’s a deep groan in the back of his throat, and then you’re moaning because he’s hilted himself inside your ass and you’ve never felt so full in your life. 

It’s nearly overwhelming how good it feels. Your eyes are already rolling back in your head, and you have to reach behind you and grip Dr. Gaster’s ribs for some sort of grasp on anything. You shudder and gasp at the feeling of their cocks, squeezing around them and moaning until you feel more used to the feeling.

Rus sees that you’ve adjusted and starts to thrust faster. “there we go, sugar. you feel so tight, _so_ good…” He huffs out a bit of a laugh as he fucks you, his cock dragging against your walls just so deliciously. You’re already trembling at his ministrations, but he adds to the pleasure by running a hand up the insides of your thighs. You’ve always been sensitive there, and it makes you squeak out an especially high moan.

“oh, you like that?” he asks you teasingly, gazing into your eyes,and that damn fanged smirk he’s cracking is unbelievably sexy.

Your professor starts to thrust in and out of you as well, albeit at a gentler pace, as your ass is much more sensitive and subject to pain. He stretches you gradually, his large cock making you burn in the best way. You adjust to the feeling slowly, as it’s odd to have two different cocks thrusting in and out of you at once, and the two men seem to be somewhat coordinated with one another in their timing. It almost feels as if there’s friction being built up inside you, hot and electric and making you moan all the same.

“Yes, that’s right… My pretty, perfect student... with your gorgeous little body…” Gaster all but growls at your ear. 

You turn to face him and his mouth hungrily collides with yours. It’s a deep kiss, one where he’s holding onto the back of your head with one of his skeletal hands as he fucks you. His tongue slides against your lips, long and smooth and dextrous enough to make you sigh. You slip your tongue against his and he groans desperately, feverishly. The sparks you feel when he bites at your lower lip are undeniable.

As Gaster kisses you, Rus hits a particularly sweet spot, causing you to arch your back a bit, moaning into the taller skeleton’s mouth. He tightens his grip on your body, phalanges digging into the skin of your hip as he thrusts harder, rougher, deeper into you. You cry out with every stroke, and it’s the cutest, most melodic thing he thinks he’s ever heard. He doesn’t know why he’s held back on you for so long, but in this moment, he can’t even fathom holding anything back. 

Rus looks at your naked body beneath him, filled with both his cock and Dr. Gaster’s, and with a newfound sense of freedom, drives himself into you to the hilt with every single thrust. The impact sends waves of pleasure through both body and his, and your pussy squeezes his cock tightly.

“_____, darlin’,” he huffs, using your name to grab your attention, “you feel so fuckin’ good, fuck… i think i’m gonna cum.” 

You look at his face, at the warmth in his eyelights and the fire-toned flush on his cheekbones, at the glint of his gold tooth and his open-mouthed smirk that’s directed at you, all for you. Slowly and steadily you lean up as much as you can in the position that you’re in, with both cocks inside you and with Dr. Gaster holding onto you and kissing your shoulders as he fucks you. 

“Then cum for me, Rus,” you rasp to him, smiling wearily, batting those eyes that drive him crazy, “Cum inside me, please?”

“sugar, you’re so- fuck, god dammit,” He grunts, and moves one of his hands to rub at your clit slowly, steadily, as he pumps his cock into you faster, and harder, groaning and growling as he reaches orgasm and shoots his hot, thick cum inside you. 

The warmth makes your body twitch, and you shudder and squeeze around both Gaster’s and Rus’ cocks as you moan louder. The feeling of Rus’ cum combined with both of their cocks, and Gaster kissing your neck is puts you right on the edge of your pleasure. Dr. Gaster smirks knowingly behind you, and moves both his hands to your nipples. He rolls his thumbs over them, then pinches them between his fingers, and at that point you don’t think anything else could make you feel any better, any hotter, than all this. 

You pant as you reach the height of your own climax, and look into Rus’ eyes as you cum on his cock with a wavering moan. Your best friend trembles with you, and Gaster groans under his breath as he feels your body tighten around him, but he fucks you through your orgasm. His cock moves in and out of you hard and fast, faster than he’s gone this whole time, and with his thrusts you don’t think you’ll ever come down from the high that you’re on. Your entire body feels so sensitive, and you can’t seem to stop making noise. 

“Such a good girl,” Gaster says as he moves you up and down on his cock, “but we aren’t finished just yet.” He picks up the pace, and moves to bite down on your shoulder. His pristine fangs dig into your skin. “Rus, do make yourself useful…” He grins at the other skeleton, a glint in his deep violet eye-lights. “I believe we can make your _girlfriend_ cum a fourth time before I do.”   
The word doesn’t slip past you, and judging by Rus’ intensifying blush it didn’t slip past him either, but you’re too busy drowning a bliss to worry about it. Instead, he gets on his knees in front of you and immediately spreads your pussy open with his fingers. His sockets seem to widen as he watches his own cum drip out of you.

“okay, i think that was the hottest thing i’ve ever seen,” he remarks, and you can’t help but giggle a little through your breathy moans. 

Nevertheless, the skeleton wastes no time in pushing three phalanges inside you and running his tongue over your clit. You cry out, still sensitive from your orgasm, and you can feel your clit twitching at the excess attention. It feels as if your whole body is throbbing, pulsing with the comedown of desire, and utterly exhausted, but you’re not quite ready to be finished, and obviously neither is your professor. Dr. Gaster pumps his cock into you deeper from behind, causing your entire form to arch and curve uncontrollably against him. 

“That’s it, dear girl,” he says, rutting himself into you faster, much faster, “I’m going to cover your gorgeous body in my cum; how does that sound?” 

“Good,” you huff, inching ever so closely to yet another orgasm as Rus sucks and nibbles at your pussy, “That sounds so good, Dr. Gaster, please, I’m so close…” 

“What was that?” Your professor snaps, his hand drawing around your neck and squeezing. “Ask me again.” His grip is tight, and his thrusts are so deep, and Rus is fucking _amazing_ with his tongue, and that edge is so close, you can just feel it.

“Please, Dr. Gaster,” you rasp, breathless, daring to look back into his eyes.

You can feel each individual thing happening one after the other, almost in slow motion. Rus’ fingers curl inside you, your breath hitches, he moans against your clit, Gaster gives one final thrust before pulling out of you with a growl, and you find your release just as he does. You tighten and clench around Rus’ fingers while Gaster finally climaxes, sending ink-colored cum over your stomach and tits. It’s messy, but it’s mesmerizing enough to send one final wave of heat through your body. You’re shaking on the desk, panting wildly from your orgasm for at least a few minutes as the two men watch you with beguiled fascination.

When you do experience the comedown, it graces you like a blanket. The tension in your body vanishes, as does all need to quiver and squirm and gasp like you were just moments before. You’re lightheaded, too lightheaded, and you struggle to truly ground yourself as you sit up on Dr. Gaster’s desk.

Your professor only has to look into your eyes for a moment before turning to Rus and saying, “There’s a compact fridge on the other side of my desk. Get her a water.” 

Your best friend only nods as he moves to find the water for you, and in the meantime, Gaster soothingly runs his phalanges over your hair. He moves his other hand to gently press against your back, gently rubbing in little circles as you breathe. 

“Are you okay, dear?” He asks, voice reduced to a soft cadence. You can’t quite speak yet, but you nod, you nod several times so he gets the message.

Rus returns, places an opened bottle of water in one of your hands and gives you one of his shit-eating grins as you take a sip. 

“so, that was some good fuckin’, amiright?”

You can’t even control how grossly you spit out your water when you laugh.

  



End file.
